Abstract

Contention based Radom Access (RA) is the procedure used by a User Equipment (UE) to establish connection with Fifth Generation (5G) network. Depending on the application scenario and network configuration, RA procedure can be either 4-step or 2-step process. 2-step RA procedure has been considered as one of the essential techniques for enabling Ultra-Reliable and Low-Latency Communication (URLC) in 5G network. On the other hand, mapping Physical Random-Access Channel (PRACH) on to a Physical Uplink Shared Channel (PUSCH) resource is a critical aspect of configuration that improves efficient resource utilization and uplink transmission. 3GPP discussion on 2-step RA procedure centered on either to support one-to-one (OTO) or many-to-one (MTO) mapping between Random-Access Channel (RACH) preambles and PUSCH resources. MTO approach is resource efficient but increases delay and decoding failure probability of PUSCH data. However, OTO approach reduces delay and decoding failure probability while increasing the PUSCH resource overhead. This paper, investigates the impact of mapping coefficient on the performance of 2-step RA and thereafter, propose A Dynamic PUSCH Configuration (DPC) scheme in which the mapping rule is configured between OTO and MTO depending on the traffic condition of the network. The performance of DPC scheme is evaluated using mathematical analysis and simulation. The results evaluated show that DPC scheme succeeds in improving the resource efficiency compared to the conventional MTO/OTO mapping rule and achieved a delay performance closer to that of OTO but far better than that of MTO.

Key words: 5G, 2-Step RA, mMTC, URLC, RACH, PUSCH, DPC, Mapping Coefficient